1. Field of the Invention
The present invention relates to a piezoelectric actuator which has a piezoelectric layer, a liquid transporting apparatus which includes the piezoelectric actuator, and a method for manufacturing piezoelectric actuator.
2. Description of the Related Art
In an ink-jet head described in US Patent Application No. 2007/0076054 (corresponds to Japanese Patent Application Laid-open No. 2007-118585), a vibration plate is arranged to cover a plurality of pressure chambers, and a piezoelectric layer is arranged on an upper surface of the vibration plate. Moreover, when an electric potential difference is generated between an individual electrode which is arranged at a portion of an upper surface of the piezoelectric layer, facing the pressure chamber, and the vibration plate as a common electrode, an electric field in a thickness direction is generated in a portion of the piezoelectric layer sandwiched between the individual electrode and the common electrode, and this portion of the piezoelectric layer contracts in a horizontal direction, and a portion of the piezoelectric layer and the vibration plate, facing the pressure chamber is deformed to form a projection toward the pressure chamber. Accordingly, a volume of the pressure chamber decreases, and a pressure of the ink in the pressure chamber rises up, thereby jetting the ink from a nozzle communicating with the pressure chamber.
Here, in such ink-jet head, for realizing a size reduction and high resolution, it is necessary to arrange the pressure chambers highly densely. However, in the ink-jet head described in US Patent Application No. 2007/0076054, when the pressure chambers are arranged highly densely and a distance between the pressure chambers becomes short, when the piezoelectric layer has contracted in the horizontal direction as described above, the portion of the piezoelectric layer facing the pressure chamber is pulled due to the contraction. Therefore, there is a possibility of occurrence of a so-called cross-talk in which jetting characteristics, of the ink jetted from the nozzle communicating with the pressure chamber, fluctuate.
Therefore, inventors of the present invention, for suppressing the cross-talk, invented an ink-jet head which will be described later. In a manufacturing process of an ink-jet head having such structure, it is necessary to carry out a polarization of the piezoelectric layer in two steps.